Databases are used in many business settings to store large quantities of business data. On occasion, data from a database is migrated to another database or back to the source database, for example, after the original data is modified. During a data migration, data from the database is typically unavailable to client applications that utilize the database. There are various mechanisms for minimizing downtime during data migration such as, for example, the use of high-speed computing devices. As the volume of data stored in databases increases, however, these mechanisms are becoming insufficient. Also, some mechanisms for minimizing downtime are not easily compatible with certain database types. For example, some mechanisms for minimizing downtime involve creating duplicates of database tables at the source database and/or the target database. When one or both of these databases are storage constrained, however, this may be expensive. For example, one or both of the target database and the source database may be in-memory databases, such as an example of the HANA system from SAP AG of Walldorf, Germany. An in-memory database stores data primarily at main memory, such as a random access memory (RAM). This is different than databases that primarily employ a disk storage mechanism. It may be expensive and/or impractical to increase main memory at an in-memory database system to create duplicate database tables during data migration.